Re: [stella] DASM 'upgrade' in progress

Subject: Re: [stella] DASM 'upgrade' in progress
From: "Eckhard Stolberg" <Eckhard_Stolberg@xxxxxx>
Date: Fri, 21 Mar 2003 22:25:29 +0100
>>
Any reasons, why the TIA constants start at offset $40?

AFAIK in all disassembled old games the registers start at $00.

Or is it just to make disassembling with DiStella a bit more compliated?
<<

Andrew is working on a game with Tigervision's 3F bankswitching,
where all accesses to addresses $3F and below will trigger the
bankswitching logic. Therefore it is nessessary to to use the
TIA mirror from $40 up.

When I sent this file to Andrew I called it VCS3F.H to differentiate
it from the normal VCS.H file. But maybe we should merge both files
and add either $00 or $40 to the TIA equates depending on a defined
constant? So the VCS.H file would look something like this:

   IFNCONST TIAOFFSET
TIAOFFSET equ $00
   ENDIF

VSYNC  equ $00+TIAOFFSET
VBLANK equ $01+TIAOFFSET
etc.

That way you could do a "TIAOFFSET equ $40" before you include the
VCS.H file when you want to write a 3F bankswitched game. If you
don't define that value it will default to $00 and all TIA addresses
will be normal.


Ciao, Eckhard Stolberg


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